RE: Axe head speed
How about the motor from [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXHHP5&P=7]this fan[/link]? It's rated for 9.6 to 10.8V. A guy put this on a Blade CP Pro and has a crazy video on rcgroups. Search for the thread over on rcgroups called '3D Video of BCPPro.'
As far as brushed motors go, is their voltage rating related to their kV?